In a recent editorial, published in the online journal Diet, Nutrition and Mental Health and Wellbeing, two members of the not for profit organisation Nutrition Society have assessed the strength of evidence in favour of low-carb diets for diabetes management.

The authors collected data from seven randomised control trials and intervention studies conducted between 2001 and 2015. All of them appeared in peer-reviewed journals and tested low-carb against high-carb, low-fat diets for managing diabetes.

Dr Sarah Illingworth and M.R. McKenzie, who are both affiliated to the London Metropolitan University, have looked at the impact of a low-carb diet on HbA1c levels, weight, changes in lipoproteins, blood sugar variability and adjustments in medication.

What they've found is that the lower the carb intake, the more significant are the reductions in HbA1c, with up to a 2.2 per cent reduction when daily carbohydrate intake is capped at 30 g.

Perhaps more interestingly is how little carbohydrate reduction (under 120g per day) is needed to have at least some impact (-0.9%) on HbA1c.

In terms of lowering bodyweight, a low-carb diet resulted in almost twice the weight loss (4.7 kg) seen with a low-fat diet (2.9) after two years.

Fasting blood sugars dropped like a rock (from 11.7 mmol/mol to 7.0 mmol/mol) very early on for many participants in response to low-carb diets.

Over half of those who consumed only 14 per cent of their total energy requirements as carbohydrate, compared to 53 per cent as per current dietary recommendations, could also safely reduce their medication.

In many cases, the reduction in medication also correlated with less instances of hypoglycemia, a two-fold greater decrease in blood sugar variability and more time spent in target or normal range.

Low-carb was also the winner in terms of treatment satisfaction and stress management, with people reporting less negative emotions during the day.

To sum up, low-fat diets at the centre of official guidelines are not optimal for diabetes management. They do not help people keep their blood sugars, weight and other very important health metrics under control as much as low-carb diets do.